1. Field of the Invention
The present invention relates to a prismatic cell and a production method for the same. In particular, it relates to a prismatic cell that has a cross-sectional shape of a rectangle, a rectangle with round corners, or the like and a production method of the same.
2. Description of Related Art
Heretofore, a prismatic cell has been known to be a cell that provides a volumetric capacity higher than that of a cylindrical cell. The conventional prismatic cell includes a prismatic cell box and a wound electrode body accommodated therein. The wound electrode body is made by winding a laminate of a positive electrode and a negative electrode each in the form of a belt as well as separators intervening between the positive and negative electrodes. The prismatic cell box is filled with an electrolyte.
In the prismatic cell, the wound electrode body has a current-collecting foil layered portion protruding on each end in a direction along an axis around which the wound electrode body has been wound, to which current-collecting foil layered portion are connected an electrode terminal and a current-collector member. With this construction, an energizing path is made shorter to decrease connection resistance and increase output. Moreover, such a construction is effective also in making the prismatic cell more compact.
To connect the wound electrode body with the collector members, for example, an electricity-accumulating element has been proposed as disclosed in Japanese Patent No. 4061938.
In the electricity-accumulating element disclosed in Japanese Patent No. 4061938, the positive and negative electrode current-collecting foil layered portions on the both ends of the wound electrode body are connected with the respective collector members in the form of a squarish U-letter by ultrasonic welding. In this case, a cantilever anvil is inserted in a space in the collector member in the form of a squarish U-letter. The current-collecting foil layered portion is sandwiched by a chip arranged on an outer periphery of the current-collecting foil layered portion and the anvil and welded to connect them.